Interconnected suspensions

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Post Sat Jan 08, 2011 7:58 pm

I've been hearing for a little while now that some of the teams are running a form of "interconnected" suspension. Ferrari is the first name to come up but Red Bull has also been thrown into the discussion.
What exactly are they talking about and how is it done? Are the front and rear suspensions somehow connected hydraulically? (Is this even legal?) Is it also related to the rumored use by teams of a spring less rear end where the third spring becomes the primary member in travel and spring rate?
simplefan
 
Joined: 20 Jan 2010

Post Sat Jan 08, 2011 11:09 pm

Depends what you mean by interconnected (left to right, or front to back). Where are you hearing this from? The former is certainly the case. The latter, not so much.

And yes, single spring rear suspension has been done.
Grip is a four letter word.

2 is the new #1.
Jersey Tom
 
Joined: 29 May 2006
Location: Huntersville, NC

Post Sat Jan 08, 2011 11:42 pm

<sarcasm>I would guess that interconnected (front to rear) suspension would be banned -- after all, it has been used on production cars for several years. </sarcasm>
Enzo Ferrari was a great man. But he was not a good man. -- Phil Hill
donskar
 
Joined: 3 Feb 2007
Location: Cardboard box, end of Boulevard of Broken Dreams

Post Sun Jan 09, 2011 7:57 am

Front to back connection and the person who has written about it is Pat Symonds.

Concept is not new or unique to F1 but if it is legal why hasn't it been used before?
simplefan
 
Joined: 20 Jan 2010

Post Sun Jan 09, 2011 10:08 am

simplefan wrote:Front to back connection and the person who has written about it is Pat Symonds.

Concept is not new or unique to F1 but if it is legal why hasn't it been used before?

Fore/aft hydraulic links were a feature of Alex Moulton's Hydragas suspension. Potential problems include fluid/hose compliance and (particularly in an F1 application), fluid volume change with temperature. Left/right Hydraulic links have been used successfully in racing, notably in the Audi R8.

The suspension of F1 vehicles includes, typically, "corner" springs, a "third" spring & an anti-roll bar. Any one of those can be omitted, provided what is left is capable of supporting the vehicle. Omitting the "corner" springs has the (logical) advantage of decoupling heave/pitch and roll support.
Last edited by DaveW on Sun Jan 09, 2011 10:18 am, edited 1 time in total.
DaveW
 
Joined: 14 Apr 2009

Post Sun Jan 09, 2011 10:13 am

simplefan wrote:Front to back connection and the person who has written about it is Pat Symonds.

Concept is not new or unique to F1 but if it is legal why hasn't it been used before?

Can you find a link?

I imagine it might be problematic to run hydraulic lines between front and back on F1 car.
timbo
 
Joined: 22 Oct 2007

Post Sun Jan 09, 2011 11:15 am

It was Pat Symonds in F1Racing magazines end of year review that highlighted the 'interconnected' suspension. there had been talk between other engineers in F1 about it before then. I spoke to Pat and he doesnt know exactly what theyre doing or how it works.
The suggestion is a link front to rear, I proposed that it was to prevent dive or squat, but I hear it might be more related to preventing warp. A mechanical linkage is unlikely to be packaged into an F1 car, so a hydraulical system that provides extra spring rate to the other axles suspension would be most likely and legal as long as it was a passive system. This could be easily packaged into the heave damper, a solution made somewhat easier by the move towards side-springless rear ends.
scarbs
 
Joined: 8 Oct 2003
Location: Hertfordshire, UK

Post Sun Jan 09, 2011 3:50 pm

It won't be to prevent warp - it will be to make the warp stiffness low without reducing roll stiffness.

The Australian company Kinetic (owned by Tenenco) and the Spanish(?) company Crueat have both done similar systems. The Kinetic system was used by Citroen I think (could be wrong) and the Crueat system was tested at Le Mans by RfH Dome. There was a Racecar Engineering on it. IIRC the low warp stiffness was good for mechanical grip, but caused issues with the aero due to reduce attitude control of the floor.

Ben
ubrben
 
Joined: 28 Feb 2009

Post Sun Jan 09, 2011 5:07 pm

to compliment Ubrben´s post
this is the RCE article about the creuat system.

http://www.carbibles.com/docs/racecar.pdf

and some info about the KINETIC´s system

.....
Where Kinetic has really made its mark is in rallying. Citroen fitted it to its Xsara rally cars in 2003 and left the rest of the World Rally competitors eating dust. For Dakar, the world’s longest and most unforgiving motor sport event, Mitsubishi added Kinetic suspension to their (already) domineering desert racers and finished 1st and 2nd in 2004 and 2005.

However, for 2006, the enormous success of the Kenetic-equipped vehicles resulted in the organizers of the WRC and Dakar events banning all forms of interconnected sway-bar or damper systems. In other words: Kinetic suspension.
....

H2 system
Image

X system
Image

RFS system
Image

a little bit more info about the different KINETIC systems can be found here

enjoy..
Last edited by 747heavy on Sun Jan 09, 2011 7:21 pm, edited 2 times in total.
"Make the suspension adjustable and they will adjust it wrong ......
look what they can do to a carburetor in just a few moments of stupidity with a screwdriver."
- Colin Chapman

“Simplicity is the ultimate sophistication.” - Leonardo da Vinci
747heavy
 
Joined: 6 Jul 2010

Post Sun Jan 09, 2011 6:11 pm

DaveW wrote:
simplefan wrote:Front to back connection and the person who has written about it is Pat Symonds.

Concept is not new or unique to F1 but if it is legal why hasn't it been used before?

Fore/aft hydraulic links were a feature of Alex Moulton's Hydragas suspension. Potential problems include fluid/hose compliance and (particularly in an F1 application), fluid volume change with temperature. Left/right Hydraulic links have been used successfully in racing, notably in the Audi R8.

The suspension of F1 vehicles includes, typically, "corner" springs, a "third" spring & an anti-roll bar. Any one of those can be omitted, provided what is left is capable of supporting the vehicle. Omitting the "corner" springs has the (logical) advantage of decoupling heave/pitch and roll support.


If the corner springs are omitted, then what supports the car? The arm flextures?
That one sounds fishy.
For Sure!!
ringo
 
Joined: 29 Mar 2009

Post Sun Jan 09, 2011 6:49 pm

vertical?
the 3rd/heave spring
plus the ARB/swaybar in roll
"Make the suspension adjustable and they will adjust it wrong ......
look what they can do to a carburetor in just a few moments of stupidity with a screwdriver."
- Colin Chapman

“Simplicity is the ultimate sophistication.” - Leonardo da Vinci
747heavy
 
Joined: 6 Jul 2010

Post Sun Jan 09, 2011 7:19 pm

Isn't the heave spring only activated at a certain ride height, and is usually of a very high spring rate to deal with high downforce?
There is free play in the sytstem up to a certain ridehieght for the heave spring.
In the case of the redbull and ferrari, the suspension seemed to be very soft at slow speed turns, so i think the very stiff heave spring is not being acted upon at those points.
The ARB will work in roll alone, and the rate depends on relative motion and force between the wheels. So the car's behavior is hard to predict and control with ARB alone.

Keep in mind i'm not a suspension guru, but no corner springs doesn't seem advantageous. It gives the engineers less control and less precision as well.
It's questionable if it even works.

The thing with the heave spring as well is that it has to be compressed at two ends to give resistance right? In the event the car rolls to the left, the left wheel compresses the heave spring, and the right pulls* at the other end as that wheel droops. * it can only pull if it is sprung.
Without a fixed or 2 compressed ends the heave spring wont give any resistance.

The same goes for the ARB when the car rolls, one end will be pushing up on it, but the other end wont be pulling down becuase there is no corner spring. The ARB need the corner springs to work, without it the resitance will only be provided by the unsprung weight therefore the relative force in the ARB will be very low.

There is a way to set the heave and ARB to act together to provide some spring force, but it's very awkward and cumbersome. As i said i'm not a suspension guru and i would like to hear how this lack of corner spring thing works, but i don't believe it makes sense.
Having the flextures act as the corner springs could be a solution, but i don't know the details in the regulation for using control arms as main suspension support, and what it takes from the materials engineers to design arms that are under such fatigue.
For Sure!!
ringo
 
Joined: 29 Mar 2009

Post Sun Jan 09, 2011 7:37 pm

as for the heave spring
what you say it´s correct to a point, the systems you discribe is common when a heave spring is combined with a corner spring.
In this case the two springs work in parallel,
where there can be a zone of "no engagement" for the heave spring ( like a bumpstop gap).

But technically it´s no problem, to use a two stage heave spring, or any combination. A heave spring does not need to be mega stiff, and can change it´s stiffness during compression/travel.

As DaveW pointed out, one advantge can be, that the springing of the two modes (roll/heave) can be tuned indepentend of each other.

A "corner spring" will work in roll&heave so it´s affecting both at the same time.
If you only wanted to stiffen the car in heave, and do it with the corner springs, you would need to soften the ARB by the same amount, if you don´t want to affect the roll stiffness at the same time.

As allways, there are different ways to skin a cat, and different people (teams/designers) will go down different routes to achieve the best compromise they see fit.
"Make the suspension adjustable and they will adjust it wrong ......
look what they can do to a carburetor in just a few moments of stupidity with a screwdriver."
- Colin Chapman

“Simplicity is the ultimate sophistication.” - Leonardo da Vinci
747heavy
 
Joined: 6 Jul 2010

Post Sun Jan 09, 2011 8:01 pm

@ Ringo
Maybe go and have a look at an F3 (or any other) monoshock suspension.
Here you have no corner springs, and only one heave spring, it may helps to
understand the system of a heave spring without corner springs a bit better/more easily.
Your heave spring, can have any stiffness you want, and can be soft, hard, progressive, linear, digressive - you decide, what you would like it to be.

Image

Image

other then that Scarbs has run an article about "corner springless rear suspension" in F1, maybe you find something there.

http://scarbsf1.wordpress.com/2010/12/0 ... evolution/
"Make the suspension adjustable and they will adjust it wrong ......
look what they can do to a carburetor in just a few moments of stupidity with a screwdriver."
- Colin Chapman

“Simplicity is the ultimate sophistication.” - Leonardo da Vinci
747heavy
 
Joined: 6 Jul 2010

Post Sun Jan 09, 2011 9:19 pm

I had the monoshock in the back of my mind, but i think it's slightly different system.

Ok, in our case if the heave spring is directly connected to both corners with no side springs...
The car's roll stiffness will be purely provided by the ARB. and this stiffness only acts as a resistance to the heave spring.
This is because a directly connected heave spring's force has to be balanced by the reaction of both wheels, since a heave spring is not anchored to the chassis like a corner spring. If the spring is not restrained, there is no force through it. The only restraint for this spring however (when both wheels are of the ground) is the ARB.

If we talk about the tuning, the two modes can be tuned independent of each other without corner springs, yes, but if the heave spring is set to act at all times like the corner spring for both sides, then the two modes are directly connected? if we follow what i was rambling about above.
The ARB is the only thing providing spring force for a heave spring constantly engaged to both corners in roll, so i would call it a dependency, especially very geometrical dependency between heave and ARB.

Which team took out the corner springs and do we have factual evidence of this?
As i said, i'm just learning and want to be clear on this.
For Sure!!
ringo
 
Joined: 29 Mar 2009

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